well i'm trying to put this code working, but it's not quiet right yet... at the moment when i click in the Save button (submit) the values are saved in the wp_options table.
For example:

in settings_section i have three settings_fields. One combo box (select_page), one input text fiel (limit_posts) and one multicheck box with blog categorys (check_categories) and bellow is the data saved in wp-options table: